[$] The state of the kernel Rust experiment

The ability to write kernel code in Rust was explicitly added as an
experiment — if things did not go well, Rust would be removed again. At
the 2025 Maintainers Summit, a session was held to evaluate the state of
that experiment, and to decide whether the time had come to declare the
result to be a success. The (arguably unsurprising) conclusion was that
the experiment is indeed a success, but there were some interesting points
made along the way.